1. Technical Field
The present disclosure relates to a liquid crystal display device (LCD).
2. Discussion of the Related Art
With the advancement of an information society, the display field of displaying electric information signals has been rapidly advanced. Accordingly, as flat display devices having advantages of a thin profile, light weight, and low power consumption, a liquid crystal display device (LCD), a plasma display panel device (PDP), an electroluminescent display device (ELD), a field emission display device (FED), and the like have been introduced and have rapidly replaced a conventional cathode ray tube (CRT). Among the flat display devices, LCDs are most widely used in laptops, monitors, and televisions (TVs) because they are excellent in displaying moving images and have a high contrast ratio.
FIG. 1 is a cross-sectional view illustrating an LCD according to the related art.
With reference to FIG. 1, the related art LCD 10 includes a liquid crystal panel having a first substrate 2 and a second substrate 4 attached to each other with a liquid crystal layer 50 therebetween, and a backlight 60. In detail, a thin film transistor Tr on the first substrate 2 includes a gate electrode 12, a gate insulating layer 13, an active layer 14, ohmic contact layers 15a and 15b, and source and drain electrodes 16 and 17, and is connected to a first electrode 19 in a pixel region P through a contact hole formed in an inter-layered insulating film 18. In addition, a black matrix 32 is below the second substrate 4, and has a lattice shape to surround the pixel region P, such that the black matrix 32 shields a non-display element, such as the thin film transistor Tr, and exposes the first electrode 19.
Further, a color filter 34 is arranged in the lattice-shaped black matrix 32 corresponding to the pixel region P, and a second electrode is arranged to cover the black matrix 32 and the color filter 34. Polarizing plates 20 and 30, each selectively transmitting a predetermined polarized light, are respectively attached below the first substrate 2 and on the second substrate 4.
In addition, a first alignment layer 31a having a surface rubbed in a predetermined direction is between the liquid crystal layer 50 and the first electrode 19, and a second alignment layer 31b having a surface rubbed in a predetermined direction is between the liquid crystal layer 50 and the second electrode 36. Thus, an initial arrangement state and an alignment direction of liquid crystal molecules are uniform. Also, a seal pattern 70 is arranged along edge portions of the first and second substrates 2 and 4 to prevent a leakage of the liquid crystal layer 50.
Because the LCD 10 is not self-luminescent, the backlight 60 is arranged as a light source below the liquid crystal panel to supply light to the liquid crystal panel. A nematic liquid crystal, a smetic liquid crystal, a cholesteric liquid crystal, or the like is used as the liquid crystal layer for the LCD 10, with the nematic liquid crystal is most commonly used.
However, in the related art LCD 10, there is an disadvantage in that an alignment process when attaching the two substrates 2 and 4 is additionally required after the substrates 2 and 4 are individually manufactured. Further, processes of printing and rubbing the alignment layers 31a and 31b to align the liquid crystal are required. Due to these processes, production rate is reduced. Moreover, a gap between the two substrates 2 and 4 needs to be maintained after attaching the substrates 2 and 4 and injecting the liquid crystal between the substrates 2 and 4. If a gap between the two substrates changes by an external pressure or impact, display quality may be degraded.